Anatomy & Physiology Chapter 4 (tissues) Notes- part 2
Anatomy & Physiology Chapter 4 (tissues) Notes- part 2 BSCI201
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This 8 page Class Notes was uploaded by mehrnazighani Notetaker on Monday October 3, 2016. The Class Notes belongs to BSCI201 at University of Maryland - College Park taught by Justicia Opoku-Edusei in Fall 2016. Since its upload, it has received 24 views.
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Date Created: 10/03/16
BSCI201: Anatomy &Physiology Chapter 4 (Tissues) Notes- Part 2 by Mehrnaz Ighani . Connective tissue (CT): the most abundant and widely distributed of primary tissues Major functions: binding and support, protecting, insulating, storing reserve fuel, and transporting substances 4 main classes: 1. Connective tissue proper 2. Cartilage 3. Blood 4. Bone . Common characteristics of CT: 1. All have common embryonic origin: all arise from mesenchyme tissue as their tissue of origin 2. Have varying degrees of vascularity (cartilage is avascular but bone is vascularized) 3. Cells are suspended/ embedded in extracellular matrix (ECM) . ECM supports cells so they can bear weight and withstand tension . All connective tissues have 3 main elements: 1. Ground substance 2. Fibers 3. Cells . NOTE: composition and arrangement of these 3 elements vary in different types of CT. Fibers and ground subs. Makeup the ECM Ground substance: o Gel like material that fills space between cells . medium through which solutes diffuse between blood capillaries and cells o Components: 1. Interstitial fluid 2. Cell adhesion proteins 3. Proteoglycans (sugar proteins) made up of protein core and large polysaccharides 4. Water (affecting the viscosity of ground subs.) Fibers: o 3 types of fibers provide support: 1. Collagen: . strongest, toughest, and most abundant type . provides tensile strength 2. Elastic fibers: networks of long, thin elastin fibers that allow for stretch and recoil 3. Reticular: . short, fine, highly branched collagenous fibers ( form from collagen fibers) . branching forms networks that offer more “give” Cells: o Blast cells: . immature cells that actively secrete ground substance and ECM fibers . fibroblasts found in CT proper . chondroblasts found in cartilage . osteoblasts found in bone . hematopoietic stem cells in bone marrow o Cyte cells: . mature, less active form of blast cell that becomes part of and helps maintain health of matrix o Other cell types in CT: (Fig. 4.7) 1. Fat cells (store nutrients) 2. White blood cells . Neutrophils, eosinophils, lymphocytes . tissue response to injury 3. Mast cells . initiate local inflammatory response against foreign microorganisms they detect 4. Macrophages . phagocytic cells that eat dead cells and microorganisms . Types of connective tissue: CT proper: consists of all connective tissues except bone, cartilage, and blood o 2 subclasses: 1. Loose CT: . Areolar . Adipose . Reticular 2. Dense CT: . Regular . Irregular . Elastic Loose CT: Areolar CT: (Fig. 4.8a) . most widely distributed CT . supports and binds other tissues . contains fibroblasts that secrete loose arrangement of mostly collagen fibers . loose fibers allow for increased ground substance, which can act as water reservoir by holding more interstitial fluid . Macrophages and fat cells are contained in spaces Adipose tissue: (Fig. 4.8b) . white fat: Similar to areolar tissue but greater nutrient storage Cells are called adipocytes Scanty matrix Richly vascularized Functions in shock absorption. Insulation, and energy storage . brown fat: Use lipid fuels to heat bloodstream rather than to produce ATP, as does white fat Reticular: . resembles areolar tissue, but fibers are thinner reticular fibers . fibroblast cells are called reticular cells Secrete reticular fibers made up of thin collagen . reticular fibers form a mesh like stroma that acts as a support f for blood cells in lymph nodes, spleen, and bone marrow Dense CT: Regular: (Fig. 4.8d ) . very high tensile strength; can withstand stretching . closely packed bundles of thick collagen fibers run parallel to direction of pull . fibroblasts manufacture collagen fibers and ground substance . very few cells and ground substance, mostly fibers . poorly vascularized . Examples: tendons and ligaments Irregular: (Fig. 4.8e) . same elements as dense regular but bundles of collagen are thicker and irregularly arranged . forms sheets rather than bundles . resists tension from many directions . found in: 1. Dermis 2. Fibrous joint capsules 3. Fibrous coverings of some organs Elastic: (Fig. 4.8f) . some ligaments are very elastic . Example: ligaments connecting adjacent vertebrae must be very elastic . also found in walls of many large arteries (arteries stretch when blood enters and recoil to push blood out) Cartilage: o Matrix secreted from chondroblasts and chondrocytes o Chondrocytes found in cavities called lacunae o 80% water, with packed collagen fibers and sugar proteins o Tough yet flexible material that lacks nerve fibers o Avascular, receives nutrients from membrane surrounding it (perichondrium) . perichondrium gives rise to chondroblasts and chondrocytes o 3 types of cartilage: 1. Hyaline: (Fig. 4.8g) . most abundant . appears as shiny bluish glass . found at tips of long bones, nose, trachea, larynx, and cartilage of the ribs 2. Elastic: (Fig. 4.8h) . similar to hyaline but with more elastic fibers . found only in ears and epiglottis 3. Fibrocartilage: (Fig. 4.8i) . properties between hyaline and dense regular tissue . strong, so found in areas such as intervertebral discs and knee . NOTE: avascular cartilage loses ability to divide as we age so injuries heal slowly. Later in life, cartilage can calcify or ossify causing chondrocytes to die. . Bone: (Fig. 4.8j) Aka osseous tissue that supports and protects body structures Stores fat and synthesizes blood cells in cavities Has more collagen compared to cartilage Has inorganic calcium salts Osteoblasts produce matrix Osteocytes maintain matrix Osteons: individual structural units Highly vascularized . Blood: (Fig. 4.8k) Most atypical CT b/c it is fluid RBCs are most common cell type Fibers are soluble proteins that precipitate during blood clotting Functions in transport and in carrying nutrients, wastes, gases, and other subs. . Muscle tissue: Highly vascularized Responsible for most types of movement Muscle cells possess myofilaments made up of actin and myosin proteins that bring about contraction 3 types of muscle tissues: 1. Cardiac (Fig. 4.9b) . found only in walls of heart . involuntary . contains striations but cells have only one nucleus . cells have many branches that join branches of other cardiac cells . Intercalated discs are special joints where cardiac cells are joined 2. Skeletal (Fig. 4.9a) . attached to and causes movement of bones . aka voluntary muscle . cells are called muscle fibers . cells contain multiple nuclei and appear striated 3. Smooth (Fig. 4.9c) . found mainly in walls of hollow organs . Involuntary . has no visible striations . spindle shaped cells with one nucleus . Nervous tissue: (Fig. 4.10) Main component of nervous system Regulates and controls body functions Made up of 2 specialized cells: 1. Neurons: specialized nerve cells that generate and conduct nerve impulses 2. Neuroglial cells: supporting cells that support, insulate, and protect neurons . Example: myelin sheaths . Covering and lining membranes: Composed of at least 2 primary tissue types Epithelium bound to underlying connective tissue proper layer 3 types: 1. Cutaneous membrane: . aka skin . keratinized stratified squamous epithelium (epidermis) attached to a thick layer of CT (dermis) . unlike other membranes, skin is a dry membrane 2. Mucous membranes: (Fig. 4.11b) . mucosa indicates location, not cell composition . also called mucosae . lines body cavities that are open to the exterior . moist membranes bathed by secretions . epithelial sheet lies over layer of loose CT called lamina propria . may secrete mucus 3. Serous membranes: (Fig. 4.11c) . also called serosae . found in closed ventral body cavities . constructed from simple squamous epithelium (mesothelium) resting on thin areolar CT . parietal serosae line internal body cavity . visceral serosae cover internal organs . cavity between layers is filled with serous fluid . special names given to show location . Example: pleurae (lungs), pericardium (heart), and peritoneum (abdomen) . Tissue repair: Repair is the function of the inflammatory process When the body’s barriers are compromised, the inflammatory and immune responses are activated Repair can occur in 2 major ways: 1. Regeneration: same kind of tissue replaces destroyed tissues so original function is restored 2. Fibrosis: CT replaces destroyed tissue and original function is lost Step 1: inflammation sets stage: (Fig. 4.12-1) . release of inflammatory chemical causes: 1. Dilation of blood vessels 2. Increases in blood vessel permeability . clotting of blood occurs Step 2: organization restores blood supply: (Fig. 4.12-2) . organization begins as the blood clot is replaced with granulation tissue (new capillary- enriched tissue) . epithelium begins to regenerate . fibroblasts produce collagen fibers to bridge the gap until regeneration is complete . any debris in area is phagocytized Step 3: regeneration and fibrosis affect permanent repair: (Fig.4.12-3) . the scab detaches . fibrous tissue matures . epithelium thickens and begins to resemble adjacent tissue . results in a fully regenerated epithelium with underlying scar tissue, which may or may not be visible . Regenerative capacity of different tissues: Tissues that regenerate extremely well: 1. Epithelial tissue 2. Bone 3. Areolar CT 4. Dense irregular CT 5. Blood forming tissue Tissues with moderate regenerating capacity: 1. Smooth muscle 2. Dense regular CT Tissues with no regenerating capacity: 1. Cardiac muscle 2. Nervous tissue of brain and spinal cord . NOTE: new research shows cell division does occur and efforts are made to increase regeneration. . Scarring can potentially cause progressive failure of the organ particularly the heart . Developmental aspects of tissues: (Fig. 4.13) Primary germ layers (superficial to deep): 1. ectoderm 2. mesoderm 3. endoderm formed nearly in embryonic development specialize to form the 4 primary tissues . nerve tissues from ectoderm . muscle and CTs from mesoderm . epithelial tissues from all 3 germ layers as the body ages, epithelia gets thin so they are more easily breached and tissue repair becomes less efficient. Works Cited Lindsey, Jerri K., Katja Hoehn, and Elaine Nicpon Marieb. Human Anatomy & Physiology, 9th Edition Elaine N. Marieb, Katja Hoehn. Boston, MA: Pearson, 2013. Print.